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Botulism is a potentially deadly illness that is caused by a toxin produced by the bacterium called Clostridium botulinum.

The bacteria are found in the soil and at the bottom of lakes, streams, and oceans. The intestinal tracts of fish, mammals, crabs, and other shellfish may contain C. botulinum and its spores. The bacterium's spores can survive in improperly prepared foods. A very small amount of the botulism toxin can cause illness. People are exposed to this toxin in one of three ways:

  • Food can be contaminated with the toxin and/or bacteria. It is the toxin produced by C. botulinum—not C. botulinum itself—that causes botulism in humans. Food that may be contaminated with the toxin include:
    • Home-canned goods
    • Sausage
    • Meat products
    • Seafood
    • Canned vegetables
    • Honey
  • If an infant swallows C. botulinum spores, they will grow in the baby's body and produce the toxin. Unlike adults and older children, infants become sick from toxin produced by bacteria growing in their own intestines. Honey is a prime source of infant botulism. Other sources include soil and dust.
  • A wound can become infected with the bacteria, but this is rare in the United States. The toxin then travels to other parts of the body through the bloodstream.
In some cases, the source of the bacteria is unknown. Botulism toxin is also a potential bioterrorism agent.

Risk Factors
Factors that increase your chance of getting botulism include:

  • Eating improperly preserved, cooked, or canned foods
  • For infants, consuming honey
  • Using IV drugs or a dirty wound—rare
Symptoms begin in the face and eyes, and progress down both sides of the body. If left untreated, muscles in the arms, legs, and torso, as well as those used in breathing become unable to move. Death can occur.

Symptoms can range from mild to severe and include:

In adults:

  • Constipation
  • Double or blurred vision
  • Droopy eyelids
  • Generalized weakness, fatigue, vertigo/dizziness
  • Muscle weakness
  • Sore throat
  • Trouble swallowing
  • Dry mouth
  • Slurred speech
  • Difficulty breathing
In babies:

  • Constipation
  • Not eating or sucking
  • Little energy
  • Poor muscle tone
  • Weak cry
When food is the cause of botulism, symptoms usually start within 36 hours of eating the contaminated food. Some people notice symptoms within a few hours. Others may not develop symptoms for several days. Some people experience nausea, vomiting, and diarrhea.

When a wound is the cause of botulism, symptoms start within 4-14 days.

The doctor will ask about your symptoms and medical history. A physical exam will be done. Blood, stool, and stomach contents will be tested for the toxin. In infants, stool will also be tested for C. botulinum. If available, samples of questionable food may also be tested for the toxin and bacteria. A wound culture will be done if wound botulism is suspected.

Your doctor may need to test other bodily fluids with spinal fluid analysis

Your doctor may need to evaluate the nerves in your body. This can be done with nerve conduction tests.

Supportive Care
The most serious complication is respiratory failure. Treatment aims to maintain adequate oxygen supply. This may require a ventilator and close monitoring in an intensive care unit. IV fluids or feeding through a tube may also be necessary.

Intubation to Assist with Breathing

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If treatment begins early, an antitoxin can stop the paralysis from progressing and may shorten symptoms. It is usually given before the disease is confirmed. It does not reverse the disease process.

Methods to Eliminate the Toxin or Bacteria
Methods to eliminate the toxin include:

  • Surgery to clean a wound
  • Antibiotics to treat a wound infection
High temperatures can destroy the botulism toxin. Strategies to prevent botulism include:

  • Do not feed honey to children less than one year old.
  • Clean and cook food throughly before eating
  • Refrigerate oils that contain garlic or herbs.
  • Do not taste foods that appear spoiled.
  • Do not eat food from a can that is bulging.
  • Boil home-canned foods for 10-20 minutes before eating.
  • Practice good hygiene when canning. Follow government recommendations.
  • Seek medical care for wounds. Return to the doctor if a wound looks infected.
  • Do not inject illegal drugs.

Centers for Disease Control and Prevention

US Department of Health and Human Services: Food Safety

Canadian Partnership for Consumer Food Safety Education

Botulism. Centers for Disease Control and Prevention website. Available at: Updated July 26, 2011. Accessed August 7, 2013.

Botulism. EBSCO DynaMed website. Available at: Updated March 6, 2014. Accessed June 16, 2014.

Botulism. website. Available at: Accessed August 7, 2013.

Botulism. website. Available at: Updated October 2011. Accessed August 7, 2013.

Last Reviewed June 2014

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